Yosemite National Park ( yoh-SEM-ih-tee) is a national park in California. It is bordered on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers 759,620 acres (1,187 sq mi; 3,074 km2) in four counties – centered in Tuolumne and Mariposa, extending north and east to Mono and south to Madera. Designated a World Heritage Site in 1984, Yosemite is internationally recognized for its cliffs, waterfalls, clear streams, giant sequoia groves, lakes, mountains, meadows, glaciers, and biological diversity. Almost 95 percent of the park is designated wilderness. Yosemite is one of the largest and least fragmented habitat blocks in the Sierra Nevada.
Its geology is characterized by granite and remnants of older rock. About 10 million years ago, the Sierra Nevada was uplifted and tilted to form its unique slopes, which increased the steepness of stream and river beds, forming deep, narrow canyons. About one million years ago glaciers formed at higher elevations. They eventually melted and moved downslope, cutting and sculpting the U-shaped Yosemite Valley.European American settlers first entered the valley in 1851. Other travelers entered earlier, but James D. Savage is credited with discovering the area that became Yosemite National Park. Native Americans had inhabited the region for nearly 4,000 years, although humans may have first visited as long as 8,000 to 10,000 years ago.Yosemite was critical to the development of the concept of national parks. Galen Clark and others lobbied to protect Yosemite Valley from development, ultimately leading to President Abraham Lincoln's signing of the Yosemite Grant of 1864 that declared Yosemite as federally preserved land. In 1890 John Muir led a successful movement to motivate Congress to establish Yosemite Valley and its surrounding areas as a National Park. This helped pave the way for the National Park System. Yosemite draws about four million visitors annually. Most visitors spend the majority of their time in the valley's seven square miles (18 km2). The park set a visitation record in 2016, surpassing five million visitors for the first time.